1. Technical Field
The present system relates generally to telecommunications and, more particularly, to any IP telecommunication technology, such as Voice over IP (VoIP) services.
2. Description of Related Art
As technology has advanced, making high-speed digital data communication networks (such as the Internet) widely available, the networks are being used for applications that are more diverse. Initially, the Internet was designed to carry data that were digital in nature, such as text files. With such digital files, Internet data transfers were satisfactory as long as the full file reached its destination in a reasonable time. Today, however, many new applications are placing real-time demands on the Internet. For example, when voice, music, video and still images are transferred, the timing of data arrival becomes crucial (or at least much more important) to the network""s usefulness in carrying the information.
In addition to the timing of data arrival, lost information, in the form of dropped packets, is unacceptable to a business that wishes to provide its customers with Voice-over-IP (VoIP) or video-over-IP in competition with legacy suppliers of these services, such as local exchange carriers and cable television providers. The importance of satisfying the needs of bandwidth-hungry applications that are crucial to the business of providers (i.e., mission-critical applications) has given rise to QoS (Quality of Service) mechanisms or controls. QoS simply means that there is some quantifiable measure of the level of service being provided. For example, packet loss rate, a maximum delay rate, a guaranteed minimum bandwidth, or a maximum allowed bandwidth, etc., may be used to measure a network""s QoS.
As high QoS becomes more important to customers, mission-critical network applications require highly reliable connections between network elements. One way to ensure high QoS is to provide 1-to-1 redundancy for each network element whose failure could result in a reduced QoS. For example, for a network element such as a packet data serving node (PDSN) board, each PDSN board can have a partner that serves as a backup.
Switching a communications network element out of service and switching to a backup element in its place is known as xe2x80x9cswitchoverxe2x80x9d. Switchover is used to implement redundancy and thus help ensure high QoS. When the out of service element recovers or is replaced, it may be switched back into service (xe2x80x9crevertive switchoverxe2x80x9d). Switchover may be accomplished using redundancy relays that are connected so that when a redundancy relay associated with a main or standby board is energized, the board will not terminate traffic. Without a method of specifically controlling when redundancy relays are energized and de-energized, however, power consumed by the relays can be relatively high if the default mode is to energize them. Energizing the relays as a default condition may be preferred, however, because it prevents interference with received and transmitted signals when switching between main and standby boards when a board is inserted into a powered chassis that is terminating traffic. Thus, a system that can control switchover mode more effectively than a fail-safe default mode is needed.
In one aspect, a system for detecting an insertion power-on of a circuit board is disclosed. The circuit board has at least one circuit board sense contact, and is insertable into a chassis. The method includes making a determination that electrical power is supplied to the circuit board before the circuit board sense contact makes contact with at least one chassis sense contact. The method further includes generating an electrical signal in response to the determination.
In another aspect, at least one circuit board sense contact can be recessed relative to one or more circuit board electrical power contacts, so that making the determination comprises detecting a voltage at a circuit board sense contact after the circuit board electrical power contact engages a chassis electrical power contact.
In another aspect, an apparatus for detecting a board-insertion power-on is disclosed. The apparatus includes a circuit board that is insertable into a chassis. The circuit board may include at least one connector, the at least one connector comprising at least one circuit board sense contact and a circuit board electrical power contact.
Upon insertion of the circuit board into the chassis, the circuit board electrical power contact will make contact with a mating chassis electrical power contact on the chassis and the at least one circuit board sense contact will make contact with a mating at least one chassis sense contact. By design, the electrical power contacts make contact before the sense contacts. When the circuit board electrical power contact and the chassis electrical power contact have made contact and the at least one circuit board sense contact but the at least one chassis sense contact has not made contact, a first voltage exists on the at least one circuit board sense contact. A second voltage exists on the at least one circuit board sense contact when the at least one circuit board sense contact makes contact with the at least one chassis sense contact.
The apparatus also includes a voltage detection circuit for detecting voltage on the at least one circuit board sense contact.